Radio transformer



Oct. 23, 1962 HlsAo MAEDA RADIO TRANsFoRMER 'Filed Dec. 16, 1959 Y i I 1a ,NVE/V705):

United States Patent O 3,060,394 RADIO TRANSFORMER Hisao Maeda, NikkatsuApt. 13, Shiba-koen, Minato-ku, Tokyo-to, Japan Filed Dec. 16, 1959,Ser. No. 859,888 Claims priority, application Japan Dec. 20, 1958 1Claim. (Cl. 336-136) This invention relates to radio transformers andmore particularly to the construction of an improved radio transformerwith a variable-inductance coil.

It is an essential object of this invention to provide such a radiotransformer of simple, compact, strong, and rigid construction, by whichthe vital, yet relatively delicate, parts and their adjusted settingsare fully protected by a substantially complete enclosure.

Said object and other objects have been achieved in the radiotransformer of this invention, the details of which will be more clearlyapparent by reference to the following detailed description of onerepresentative embodiment of the invention when taken in connection withthe accompanying drawing, lin which the same parts are designated by thesame numerals, and in which:

FIG. 1 is a front elevational view, in section, of one embodiment ofthis invention, in assembled form;

FIG. 2 is a plan view of the integrally fastened base and side postswith the ferromagnetic cylinder removed;

FIG. 3 is a top plan view of the magnetic cylinder of the embodiment ofFIG. 1;

FIG. 4 is a rear plan view of the magnetic cylinder of the embodiment ofFIG. l;

FIG. 5 is a top plan view of the magnetic core of the embodiment of FIG.l;

FIG. `6 is a front elevational view of the ferromagnetic core of theembodiment of FIG. l.

Referring to the drawing, the basic structure of the illustratedembodiment comprises a base 3, fabricated from an electrical insulationmaterial, for example, synthetic phenol. resin, onto which has beenintegrally or rigidly afxed two supporting posts 2 and 2a, which standsymmetrically on diametrically opposite sides of the center of said base3, and which have inner surfaces mutually opposed and threaded withfemale screw threads 1 and 1a so formed as to receive and engage withthe male screw threads 6 on the upper head portion of an invertedferromagnetic cylinder 7. The base 3 centrally supports and partiallyencloses a drum-shaped, ferromagnetic core 5, about which is wound acoil 4. The aforesaid cylinder 7 is screwed down by means of a screwdriver inserted into the slot -8 on the top of the cylinder 7, inbetween said posts Z and 2a, to cover the core 5 and coil 4 and tocontact with said core 5 centrally through a protruding pivotal point 9disposed centrally 3,060,394 Patented Oct. 23, 1962 "ice on the lower,internal surface of the head portion of said cylinder 7.

The inductance of the aforesaid coil 4 may be varied by turning themagnetic cylinder 7, thereby raising or lowering said cylinder and itspivotal point 9 which is a unique feature provided so as to affordextremely llow frictional resistance between said point 9 and said core5 against rotation relative to one another, thereby enabling thecylinder 7 to be turned at will yfor the purpose of adjusting the coilinductance as described above without causing the rotation of the core Sthrough frictional contact, and thereby preventing breakage of theleadout wires of the coil 4.

The pivot 9 is made of the same ferromagnetic material as the cup core7. When the pivot 9 is in contact with the upper surface of the drumcore 5 as shown in FIG. 1 the inductance is practically the same as whenthe cup core provided with no such pivot is made in contact with thedrum core.

It is desirable to obtain the maximum possible inductance in order toachieve the maximum range.

While I have described one particular embodiment of my invention, itwill, of course, be understood that I do not wish my invention to belimited thereto, since many modifications may be made and I, therefore,contemplate by the appended claim to cover all such modifications as mayfall within the true spirit and scope of my invention:

What I claim is:

A radio transformer, comprising a base made from an electricalinsulation material; supporting posts rigidly affixed thereto,symmetrically disposed thereon in diametrically opposed juxtaposition,and constructed so as to receive and support a magnetic cylinder; adrumshaped, high-frequency, ferromagnetic core disposed centrally onsaid base; a coil wound about said ferromagnetic core; and said magneticcylinder which substantially envelopes said coil and said core in theassembled state, and which has a central protruding pivotal point forcontacting the top of said magnetic core and, by the raising andlowering of said magnetic cylinder with respect to its said supportingposts, for varying the inductance of the said coil, the point contact ofsaid protruding pivotal point preventing any rotational torque frombeing transmitted, by friction, from any rotational motion of saidmagnetic cylinder to said magnetic core.

References Cited in the le of this patent UNITED STATES PATENTS2,168,351 La Rue Aug. 8. 1939 2,435,630 Ketcham Feb. 10, 1948 2,748,357Garcia May 29, 1956

